when show databases/tables/table status where xxx, it will change a selectStmt to select result from
information_schema, it need catalog info to scan schema table, otherwise may get many
database or table info from multi catalog.
for example
mysql> show databases where schema_name='test';
+----------+
| Database |
+----------+
| test |
| test |
+----------+
MySQL [internal.test]> show tables from test where table_name='test_dc';
+----------------+
| Tables_in_test |
+----------------+
| test_dc |
| test_dc |
+----------------+
1597afcd67